Some mammals are sensitive to the Earth's magnetic fields. Several scientists recently published a study in Frontiers in Zoology asserting that dogs are among them. They discovered that when dogs are urinating or defecating, they tend to align their bodies along a magnetic north-south axis:

We measured the direction of the body axis in 70 dogs of 37 breeds during defecation (1,893 observations) and urination (5,582 observations) over a two-year period. After complete sampling, we sorted the data according to the geomagnetic conditions prevailing during the respective sampling periods. Relative declination and intensity changes of the MF during the respective dog walks were calculated from daily magnetograms. Directional preferences of dogs under different MF conditions were analyzed and tested by means of circular statistics. [...]

Dogs preferred to excrete with the body being aligned along the North-south axis under calm MF conditions. This directional behavior was abolished under Unstable MF. The best predictor of the behavioral switch was the rate of change in declination, i.e., polar orientation of the MF.

This discovery could have practical use. Let's say that you're lost in the wilderness. It's nighttime, so you can't gauge your direction by the sun. It's cloudy, so you can't see the stars. Give a dog some food (maybe food with glitter in it) and wait for nature to take its course. Then at least you'll narrow your direction down to a single axis.

OK, I am pretty sure this applies pretty well to my dog. It's not all the time, but seems to be the case most of the time I've looked.Speaking of looking . . . I hate to think of what those two years of research were like, with the thousands of observed 'events'. That is one sad, sad graduate student somewhere there.